Christian Saumweber

Comparison the Cooling Performance of Cylindrical and Fan-Shaped Cooling Holes With Special Emphasis on the Effect of Internal Coolant Cross-Flow

Cooling holes in real gas turbine applications are prevalently exposed to cross-flow in the coolant passage. The majority of the studies available in literature do not consider the effects of flow in the coolant passage. Our own studies however reveal that especially diffuser holes are very susceptible in respect to cross-flow at the hole entrance, if the orientation of the cross-flow is perpendicular to the symmetry plane of the cooling hole. The effect of coolant cross-flow will be discussed in detail. The superordinate target is to identify the dominating mechanisms, which determine the flow field within the diffuser hole and hence limit the potential of cooling performance augmentation. For this reason a fan-shaped hole with 14° expansion angle will be compared to a simple cylindrical hole. Both holes have a length-to-diameter ratio of 6 and an inclination angle of 30°. The comparison will be performed by means of experimentally gained discharge coefficients, local and laterally averaged adiabatic film cooling effectiveness, and heat transfer coefficients. Numerical simulations of the cooling flow will support the interpretation of the experimental results.Copyright

Effect of Geometry Variations on the Cooling Performance of Fan-Shaped Cooling Holes

The flow conditions at both, the cooling hole exit as well as the cooling hole entrance affect in a very different way the cooling performance downstream of cylindrical and fan-shaped holes. The consequences of a change in a flow parameter very obviously depend on the respective hole geometry. To gain an as complete as possible view of the specific effects of varying operating conditions and hence an enhanced understanding of the dominating mechanisms, a variation of the hole geometry is imperative. The expansion angle of the diffuser, the inclination angle of the hole, and the length of the cylindrical part at the hole entrance are considered to be the most important geometric parameters of diffuser holes. The effect of a change of exactly these parameters on the film cooling performance will be analyzed. For a better assessment of the characteristic effects associated with contouring of the hole, every dif-fuser hole is compared to an adequate cylindrical hole. The comparison will be performed by means of discharge coefficients and local and laterally averaged adiabatic film cooling effectiveness and heat transfer coefficients derived from experiments.Copyright

Ansaugmodul mit Indirektem und Integriertem Ladeluftkühler

In einem gemeinsamen Projekt haben Behr und Mann+Hummel die direkte und die saugrohrintegrierte, indirekte Ladeluftkuhlung in einer Fahrzeugmessung im Windkanal miteinander verglichen. Im Vergleich zur Serienlosung mit direkter Ladeluftkuhlung konnte mit einem Prototypen-Ansaugmodul (Saugrohr mit indirektem saugrohrintegrierten Ladeluftkuhler) eine signifikante Reduzierung des Ladeluftdruckverlusts, eine sehr homogene Temperaturverteilung in den Schwingrohren und eine deutliche Reduzierung des Ladeluftvolumens zwischen Verdichter und Motoreintritt erreicht werden.

Free-Stream Effects on the Cooling Performance of Cylindrical and Fan-Shaped Cooling Holes

From literature and our own studies it is known that the effects of hot gas cross-flow and in particular the turbulence of the hot gas flow highly influence the spreading of the coolant in the near hole vicinity. Moreover, the velocity of the hot gas flow expressed by a hot gas Mach number obviously plays a much more important role in case of diffuser holes than with simple cylindrical holes. To realize a certain blowing rate, a higher pressure ratio needs to be established in case of higher Mach numbers. This in turn may strongly affect the diffusion process in the expanded portion of a fan-shaped cooling hole. The said effects will be discussed in great detail. The effects of free-stream Mach number and free-stream turbulence, including turbulence intensity, integral length scale, and periodic unsteady wake flow will be considered. The comparative study is performed by means of discharge coefficients and by local and laterally averaged adiabatic film cooling effectiveness and heat transfer coefficients. Both cooling holes have a length-to-diameter ratio of 6 and an inclination angle of 30°. The fan-shaped hole has an expansion angle of 14°. The effect of the coolant cross-flow at the hole entrance is not considered in this study, i.e. plenum conditions exist at the hole entrance.Copyright

Intake module with indirect integrated charge air cooler

Within a common project of Behr and Mann+Hummel a comparison between direct and indirect charge air cooling integrated in the intake manifold was carried out by vehicle measurements in the wind tunnel. In comparison with the series-production solution based on direct charge air cooling, a prototype intake module (intake manifold with integrated indirect charge air cooler) significantly reduced charge air pressure loss, provided a highly uniform temperature distribution in the runners, and reduced the charge air volume between the compressor and point of entry into the engine.